Grand Admiral Thrawn is possibly the greatest threat to ever face the Rebellion and the New Republic. His deep knowledge of different races' history, art, and philosophy gave him an edge in combat unlike any other commander. His 7th Fleet wreaked all sorts of havoc, being led by Thrawn's flagship, the Chimera. Soon, you'll be able to add this unique ISD to your fleets. But what other sorts of tricks with Thrawn have up his sleeve? You can see for yourself in this preview.

From the post:

Within this Expansion Pack, you’ll discover a new Imperial-class Star Destroyer, emblazoned with Grand Admiral Thrawn’s chimaera sigil. This difference is merely on the surface level, but you’ll soon discover that Thrawn’s changes to the way you build and fly your fleet go far beneath the surface. The changes start with two new types of ship cards that you can use to refit your Imperial Star Destroyers—the Kuat Refit and the Cymoon 1 Refit. Both new ship cards offer new variants of upgrade bars and attack dice that you’ll be able to use to batter the Rebellion into submission in entirely new ways.